Apparatus fob molding helical



April s, 1947. F, W, ORTMAN 2,418,599

APPARATUS FOR MOLDING HELICAL SCREWS Filed Oct. 2, 1944 FQQNK WasLeY ORTMnN BYHBLMW Patented Apr. 8, 1947 UNITED STATES PATENT GFFICE APBARATUS'FOR MOLDING HELICAL SCREWS FrankWesley Ortman, Sandusky, Ohio, assignor toA Farrell-Cheek Steel Company, Sandusky, Ohio, a corporation of' Ohio Application October 2, 1944, Serial No. 556,775

1 Claim.

This invention relates to improvements in an apparatus for molding helicalv screws particularly when the screw patterns are off such` length as tofbend somewhat in the middle during mold- [ing andY ramining when supported at the ends only Long helical screws are used for feeding coal in stokers and in conveyors of the feed-screw type used in many industries. It is desirable in all cases that the screw be as near straight as possible. with the outermost elements of the screw night lying on a true cylinder, Various methods known to me have beenproposed for producing this result, Ibut to the best of: myknowledge, none of them is suited for the rapid production ofV uniformly high quality screws such asare made possible by the present invention.

In the drawings,

Fig. 1 is an elevational view showing fiask and pattern supported in my improved manner with a sand-slinger in position to ram sand into the mold;

Fig. 2'is an enlarged top plan view of the flask and pattern of Fig, 1;

Figs, 3 and 4V are sectional views taken along similarly numbered lines ofv Fig. 2;

Fig. 5V is an end view taken from the position of line `5--5 of Fig. 2 while Fig. 6 is a View similar to Fig. 4 showing a.`

modifiedV form of brace.

My invention is described as used in the for,- mation of a helical screw I' (which represents both the screw formed andthe pattern for forming it) of such length and cross-sectionaldimensions that it bends in the mid portion of the screw when supported at the ends only. The screw comprises an axially-extending cylindrical shaft portion lila,` about which is disposed a helical iiight Ib of the type generated by a straight line extending radially outwardly from one side of the shaft portion lila and travelling spirally along the shaft from one end of the same to the other. It shouldv be understood that the purpose of the present invention is to cast the shaft and night integrally in one operation and have the same absolutely true and straight from end to end.

Y The flask II comprises two? parallel side walls I la, preferably, but not necessarily, connected together at one end by the steel section I2 held in place by the hinges I3. Wooden end walls IIb and IIc are provided. The end wall IIb has end tongues IId which extend through suitable openings in the side walls IIa, and when the flask is assembled as shown in Figs. 1 and 2,

wedges I4 are passed through openings in these tongues so as to hold the side wallsl Iilc firmly against the shoulders of theend wall; IIIfb, and the flask side walls are kept. from spreading out,- wardly by the pressure of the wedges; I-4 at one end and by the st eell section IZ at, the.; opposite end. The end wall` IIc is heldM properly` spaced from the steel section I2l for the accommodation of screws ofvarious length by Wood spacer blocks I5, It will be noted that; the: iiask is` Open top and bottom and; when a, moldingv operation` is to be performed, the ask is. placed upon a Suitable surface such as the base channel I6.

The screw pattern is: is carefiully iormd in the shape or the screw to be cast.` Thisfpattern is supported inthe flask by the. following means:

At the left end, as viewed'l in` Figs. 1 and 2,

I a stripper block Il suitably supported. on the end wall IIb is provided with an axially-extendingu central opening adapted to receive theshaft Illa and a helical slot (seen at; Ii''c).` for receiving theflight lilo. At the` right-hand end, a .Core printv I8, receives the other end ofthe screw pattern. Intermediatev the ends` of: the screw;A and preferably at about its mid point, additional'. rigid means is supplied for. supporting the screwA in fixed relation to theask, but it is held, posi-,- tion chiey by the sand rammedy in the nasi; and remaining in position during the` casting opera;- tion.

This rigid support means', in the present case, comprises two plates: IS and A2Q of cast Steel .or other rigid material' as laterdisclosed. The plates may be of butterfly-wing shape as best seen in Fig. 4'. These plates: are alike', and one only-Will be described, the.` parts. of` the `other-being given similar referencefcharacters', The plate` IEl,` has a nat. bottom face I9@V of limited ,extent which rests firmly on the base member I6. The out.- side .edge I9b slopes upwardly and outwardly from the base ISa and rests firmly against. a, block of Wood or the like ZI? which ts yin thelowercorner of the ask at this point. The upper, outeredge of the plate rIilc'is cut ,atright anglesto thebotitom I9a so that it rests firmly against the top portion of the flask side wall` Ilia. The top; .of the plate at ld is level withA the topA of thefflask. Thev edges of the plate which face inwardly, namely, 19e and ISf, are inclined inwardly to a face I9g of limited extent and lying approximately along the axis of the screw pattern I0. In position to closely embrace the screw shaft Ia, the edge IEIy of the plate is provided with a substantially semicircular recess opening inwardly. Before the ramming operation, the

' 3 plates I9 and 20 are placed as shown in Figs. 2 and 3 approximately at right angles to the axis of the screw pattern and spaced apart longitudinally of the same sufficiently so that; as later described, the screw pattern may be threaded out of the mold, the flight I 9b being enabled to pass between the plates I9 and 29. f In Fig. 3, I have shown plate I9 positioned at a point where the iiight Illb extends horizontally toward the right, as viewed in Fig. 3, away from the recess in the edge I9g, while in Fig. i, I have shown tally toward the left away from the recess in the plate edge 20g. However, it will be understood that any position of the plates I9 and 2E! on opposite sides of the screw pattern fairly close together near the longitudinal center of the pat-` tern is satisfactory so long as the screw flight may pass between the plates upon rotation of the pattern. A

A C clamp 22 of known type is placed under the plate I6 with its parallel sides extending upward and against each side of iiask IIa. A wooden wedge .23 is then inserted between one side of the ask and one side of the C clamp. This wedge is driven in with a hammer which tightens the supports I9 and 29 and also prevents the flask IIa from spreading when the sand is rammed in the flask. The clamp is shown in Figs. 2 and 3 but omitted in other views for clearness.

With the parts in the position shown, the molding sand is rammed in the ask IIa. This operation may be accomplished by hand but I prefer to use the sand-slinger 2l shown in elevation in Fig. 1. This sand-'slinger is of the type shown in Patent No.12,212,510, granted August 27, 1940,

to Murray G. Clay and Elmer O. Beardsley, although it will be understood by those skilled in this art that anysimilar device may be used. In operation, this sand-slinger throws a stream of sand at high velocity from the impeller Zia through' the opening 2lb substantially vertically downward. The head of the device is manipulated by means of the handle 2 Ic. I prefer to use a powerful sand-slinger of this type because a stream of sand directed downwardly in the ask on either sideof the screw pattern causes the sand to iiow inwardly and upwardly beneath the pattern so as to fill all voids around the screw l .and particularly beneath it. To aid in the iiow Iof sand around the pattern near the plates I9 and 29, I Apreferably provide large openings vthrough the mid portion of these plates as indi-` `cated at I9h and 20h. Also, the diverging edges :|9e and 20e above the pattern and I9f and 29j nelow the pattern leave plenty of room for the 110W of sand onopposite sides of the plates I9 and 20.

When the ilask is completely filled, the sand is struck off level across the upper edges of the ilask.

-Suitable sprues or gates are provided at the opposite ends of the mold communicating with the prints I'I and I8, and the screw pattern is then rotated to remove it from the mold. This action takes place without any disturbance of the molding sand throughout the long length of the screw because in the first place, `the screw pattern Ill the plate 29 positioned at a point where the flight lUb of the screw pattern extends horizon-V the metal has hardened sufliciently, the casting is stripped from the flask. .The plates I9 and 20 do not fuse with the metal-of the casting and fall away freely.

I may substitute for the steel plates I9 and 20,

other hard, rigid material forming a pair of braces of similar character for supporting the long screw pattern against bending in the middle during ramming. In Fig. 6, I show such substitute braces 24 and 25 made of core sand properly formulated, molded and dried and having suilcient strength and rigidity to replace the' steel supports previously described. The'cores 24 and 25 are rectangular in shape extending from the sides of the flask IIa to the exact center to the shaft of the screw pattern, being placed like plates I9 and 20, thus holding the pattern in exactly the same manner and for the same purpose as the steel plates I9 and 29. The cores are held in place by blocks 25 which support the outer ends while the `pattern shaft holds the inner ends.

I have thus provided a method and apparatus for casting elongated screws quickly and accurately with ordinary foundry help. This process produces this type of screw more rapidly and with fewer rejections than any other process known to me for the production of the same article.

Apparatus for integrally casting a long screw having a cylindrical shaft about which is disposed a helical flight extending radially away from said shaft, comprising an elongated ask, a screw pattern of the screw to be cast, two upright braces supported in'said flask from opposite sides thereof and intermediate the ends of the flask, said braces extending above said shaft, there being recesses in said braces opening laterally inwardly and adapted to half embrace said shaft of said screw pattern respectively on opposite sides thereof, and said braces being spaced apart longitudinally of said screw pattern suciently to permit the flight thereof to pass between said braces after sand is rammed in said flask about said pattern and said pattern is screwed out of the sand'by rotation about its axis.

FRANK WESLEY ORTMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED srAfrEs4 ElrrEN'rs.l

l British 1895 

